Impact tool

ABSTRACT

A pneumatically driven impact tool particularly suited for use in delivering impacting blows to a working surface, characterized by an hermetically sealed housing including therein an impact head and a plurality of interrelated valves adapted to be coupled with a source of pressurized fluid for imparting reciprocating displacement to the impact head. A particular feature of the tool includes a simplified pilot valve operatively coupled with the impact head in a manner such that a cycle of operation of the impact tool is initiated as the impact head forcibly is positioned against a working surface.

United States Patent Smith IMPACT TOOL [76] Inventor: Arthur J. Smith, P.(). Box 3274,

Visalia, Calif. 93277 [22] Filed: Nov. 24, 1972 [21] Appl. No.: 308,948

Related US. Application Data [63] Continuation of Ser. No. 46,427, July 2, 1970,

abandoned.

[52] US. Cl. 91/220, 91/41] A [51] Int. Cl. Flb /04 [58] Field of Search 91/220; 173/16,

[56] 7 References Cited UNITED STATES PATENTS 1.044.263 ll/l9l2 Schumacher 173/16 June 4, 1974 Primary ExaminerPaul E. Maslousky Attorney, Agent, or Firm-Huebner & Worrel 5 7 ABSTRACT A pneumatically driven impact tool particularly suited for use in delivering impacting blows to a working surface, characterized by an hermetically sealed housing including therein an impact head and a plurality of interrelated valves adapted to be coupled with a source 12 Claims, 6 Drawing Figures 566R My 40 54'- 4 I06 4 6 152 4 4 00 h Q72? ,94

3a a 3R PATEMTEBM 4 m4 SHEEK E W 2 ARTHUR J. SM/TH INVENTOR A TTORNEVS IMPACT TOOL 1 This is a continuation of application Ser. No. 46,427,

- filed July 2, 1970, now abandoned.

BACKGROUND OF THE INVENTION The invention relates to impact tools and more particularly to manually supported, lightweight and pneumatically driven impact tools of a type adapted to be manually positioned and supported in an operative disposition relative to selected working surfaces of a broad assortment.

The prior art includes numerous manually manipulated impact tools, including electrically and pneumatically operated hammers. Among these devices are those which are adapted to betriggered in response to a positioning thereof against adjacent selected working surfaces. Quite frequently, such tools employ pneumatic motors for developing an impacting output consisting of a series of hammer-like blows-To achieve such an output, certain heretofore available impact tools employ structure which frequently is bulky, complex and often quite heavy. Therefore, in certain operative environments, utilization of the heretofore available impact tools is inhibited, particularly in those instances wherein a high degree of manipulation and delicate control of the tool is required. Furthermore, abatement of noise and vibration generally is of prime concern, particularly where operators are required to perform delicate tasks over relative long intervals. While the impact tool disclosed in applicants prior US. Pat. No. 3,438,449 functions quite satisfactorily,

it has been found desirable to provide an even further OBJECTS AND SUMMARY OF THE INVENTION It therefore is an object of the instant invention to provide an improved impact tool.

It is another object of the instant invention to provide an improved impact tool particularly suited for manual manipulation.

It is another object of the instant invention to provide a pneumatically actuated impact tool, including an operative association of improved components, which serve to provide an improved impact tool of a lightweight, and simplified construction.

It is another object of the instant invention to provide a pneumatically actuated impact tool particularly suited for use as a hand-held operative tool.

It is another object of the instant invention to provide a pneumatically actuated impact tool which is of a simplified and efficient structure, adapted to be rendered cyclically operable in response to a positioning thereof adjacent to a selected working surface and is of a practical size for conducting delicate manual operations over extended periods of time.

It is another object of the instant invention to provide a pneumatically actuated impact tool including a sealed housing having a reciprocable impact head seated therein and adapted to be extended from the housing in response to a gated pulse of pressurized fluid delivered directly thereto and caused to impinge thereon for achieving an impacting blow, all in response to a positioning of the impact head in operative engagement with a selected working surface.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an impact tool which embodies the principles of the instant invention.

FIG. 2 is a cross sectional view of the impact tool, taken generally along line 2-2 of FIG. I, with the impact head thereof being disposed in an impact disposition.

FIG. 3 is a cross sectional view, similar to FIG. 2, il-

lustrating an initial displacement of the impact head as its impact surface operatively is caused to engage a working surface for thereby initiating a retracting stroke of the head during a single cycle of operation. FIG. 4 is a cross sectional view, quite similar to FIGS. 2 and 3, illustrating a retracted disposition assumed by the impact head as it is fully retracted and an impacting stroke is initiated.

FIG. 5 is a cross sectional view, quite similar to FIGS.

2, 3 and 4, illustrating a position assumed by the impact head during an impacting stroke thereof, prior to its assuming the impact disposition illustrated in FIG. 2.

FIG. 6 is a partially sectioned, perspective view of selected valve components and the impact head shown in FIGS. 2 through 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views there is shown in FIG. 1 an impact tool which embodies the principles of the instant invention.

The tool includes a housing 10 which, as a practical matter, is fabricated of any suitable material, including aluminum, stainless steel and the like. Preferably, the housing 10 is configured to seat in the palm of an operators head so that the device can, with minimum effort, be manually manipulated relative to selected 'working surfaces. The housing 10 includes a chambered body 12 closed by a head plate 14. The head plate is coupled to the housing 10 employing any suitable means including a plurality of screws 16 threadingly received within suitable screw-threaded openings 18 appropriately provided within the body 12.

Within the body12 there is provided a fluid inlet chamber 20 which, as a practical matter, is coupled with a suitable source of pressurized fluid, not shown, through a screw-threaded fitting 22 seated in a wall of the housing body. Also provided within the body there is a cylindrical chamber which serves as an actuator bore 24 extending from the chamber 20 to an annular output opening 26 which is provided within the body 12 at a point remote from the plate 14.

Within the actuator'bore 24 there is seated for reciprocation an impact head 30. The head 30 is configured to conform to a thickened disk having a cylindrical peripheral surface 32 and a transversely related impact 3 surface 34. The surface 34 functions to deliver a series of impacting blows as an operation of the tool is achieved.

While the impact head 30 can be fabricated from various metals, including aluminum and the like, a head fabricated from suitable synthetic resins functions quite satisfactorily. Where the overall weight of the tool and the total momentum developed are of prime consideration, synthetic resins often in the fabrication of the impact head 30 are preferred over metals. such impact heads are more fully disclosed and discussed with more particularity in'a copending application.

It is to be understood, of course, that the peripheral surface 32 continuously is in operative engagement with the internal surfaces of the actuator bore 24 so that the head 30 is guided thereby as it is driven in axial reciprocation relative thereto. However, within this surface there preferably'is provided an annular groove 36 within which there is seated an O-ring 38 in order than an hermetic seal be established and maintained between the cylindrical surface 32 and the internal surface of the actuator bore 24. Consequently, the opening26 continuously is sealed against an expulsion of pressurized fluid.

' The actuator bore 24 also is sealed by a reciprocating shuttle valve, generally designated 40, FIG. 2, in a manner such that an expandible chamber 4-1 is established therebetween. The shuttle valve 40 is formed as an elongated, spool-shaped member which is adapted to be reciprocated along its longitudinal axis alternately to establish and interrupt communication between the inlet chamber 20 and the bore 24. Sealing of the bore ing defined between the seat 43 and the shoulder 46, as best illustrated in FIGS. 4 and 5.

The opposite end of the shuttle valve supportingly is received within a cylindrical bore 50, coaxially related to the bore 24 and formed within a projected cylinder 54. This cylinder is fabricated within the head plate l4.and axially'extends into the body 12 to seat within an opening 56 suitably formed in the body 12. About the cylinder 54 there is provided an annular shoulder 58 which receives therein an O-ring 60 for sealing the cylinder 54 relative to the chamber 20 as the head plate 14 is mounted on the body12.

Hence, it can be appreciated that once the head plate 14 is coupled with the body 12, through the use of the screws 16, axial reciprocation of the shuttle valve 40 is accommodated. However, in order to achieve a desired hermetic seal between the internal surfaces of the bore 50 and the external surfaces of the shuttle valve for thus maintaining a fluid-tight integrity for the chamber 20, an O-ring 62 is mounted inan annular groove 63 formed about the periphery of the shuttle valve.

The O-ring 62, in effect, serves to isolate the inlet chamber 20 from an exhaust chamber 64.'This chamber coaxially is related to the cylinder 54 and communicates through an exhaust passage 65 with the atmosphere. The exhaust chamber64 is defined by an annular lip-like protrusion 66 concentricaly related to the cylinder 54 and extended from the head plate This 24, by the shuttle valve 40, is achieved through an annular seal42 which circumscribes an end portion of the peripheral surface of the shuttle valve. The seal 42 is provided with an annular, chamfered seat 43 and is supported by an annular surface 44 radially extended from the external surface of the shuttle valve, FIG. 6.

The purpose of the annular seal 42 is to hermetically isolate the chamber 41 from the chamber 20. This function is accomplished as the seat 43 forcibly is positioned against an annularshoulder 46 having a chamj shoulder 48, which also includes a radially extended pressure face 49 disposed within a plane parallel to the plane of the surface 44. The surface 49 acts as a confining surface for fluid'under pressure as the fluid is retained within the chamber 20. In practice, the fluid acts against the surface 49 with a force sufficient to assure that the seat 43, as it acts against the face of the shoulder 46, establishes an hermetic seal therebetween.

Consequently, when the seat 43 of the seal 42 is forced against the face of the shoulder 46, the bore 24, and therefore the chamber4l, hermetically is isolated from the fluid confined within the chamber 20. However, as the seal 42 is displaced from engagement with the shoulder-46the chamber 41 pneumatically is charged by a pulse of pressurized fluid developed as the fluid surges from the chamber 20 through an annular openprotrusion is so arranged as to seat against an annular seal 68 circumscribing an adjacent annular end surface of the shuttle valve 40. The seal 68 is supported by an annular shoulder 69 formed along the external surface of the shuttle valve. When the shuttle valve 40 is so positioned that the seal68 is in sealing engagement with the surface of the lip, 66 an hermetic seal is established therebetween. Thus the exhaust chamber 64 hermetically is sealed from the exhaust passage 65.

The exhaust chamber 64 is in constant communication with a coaxially related bore 70 which axially extends through the body of the shuttle valve 40 and receives therein a pilot valve 72. Asbest illustrated in FIG. 6, the pilot .valve 72 includes a valve head 74 terminating in an annular transverse surface 75. The pilot valve also includes an integral, coaxially relatedjvalve stem 76 which extends from the surface 75. The peripheral surface of the valve head 74 isof a cylindrical configuration and operatively is reciprocated within the bore 70 alternately to seal and'to open an inlet passage 78 extending radially from the bore through the body of the shuttle valve 40. This passage is provided for permitting the bore 70 and the chamber 20 to be associated in operative. communication, whereby fluid under pressure can directly be delivered from the inlet chamber 20 to the bore 70.

The inlet passage 78 is sealed by a pair of O-rings 80, FIG. 6, which is seated in the surface of the bore 70, at opposite-sides of the passage and together, with the external surface of the valve head 74, is adapted to establish an hermetic seal for isolating the chamber 20 from the bore 70.

The stem 76 includes an externally threaded terminal portion .81 adapted to be threadingly received within a screwthreaded, concentrically arranged bore 82 axially extended into impact head30. This bore is provided in a coaxial relationship with the impact surface 34. Hence, it is to be understood that as the impact head 30 is reciprocated relative to the internal surface of the bore 24, the valve head 74 simultaneously is reciprocated within the bore 70 of the shuttle valve for thereby opening and closing the radially extended passage 78 whereby communication between the bore 70 and the chamber alternately is established. As can readily be appreciated, the seat 43 of the seal 42 alternately is seated and unseated as a reciprocation of the head is achieved.

With particular reference to FIG. 3, it is noted that as the impact head 30 is forced upwardly, through a distance sufficient for permitting the valve head 74 to open the passage 78, fluid under pressure is permitted to escape from the chamber 20 to the bore 70 through the passage 70 to impinge on the annular surface 75 of the valve head 74. This impingement is sufficient to accelerate the valve head 74 in its upward displacement. The thus imparted accelerated motion serves to lift the impact head30 for thereby drawing the impact head into the bore 24 for causing the impact head to be disposed in its retracted disposition.

Of course, as the impact head 30 is drawn intothe bore 24 it is preferred that a discharge of fluid entrapped within the chamber 41 be accommodated. This discharge is accommodated by providing within the chamber 41 a fluid discharge unit 83 extended concentrically therethrough. This unit includes a plurality of radially extended fluid discharge ports 84 formed within a sleeve 86 concentrically related to the stem 76. The sleeve 86 is provided with an annular base 88 seated in an annular recess 90 established within the surface of the impact head 30 in circumscribing relationship with the bore 82. The internalsurface of the sleeve 86 provides a fluid passageway 92 extending along the external surface of the stem 76. A plurality of radially directed ports 94 are provided within the stem 76 at a point adjacent to the surface 75 of the valve head 74. These ports intersect with a concentric bore 96 established within the body of the stem 76 and extended through the valve head 74 of the pilot valve 72 so that a fluid path continuously is established between the chambers 41 and 64.

The sleeve 86, of course, is reciprocated within the bore 70 of the shuttle valve as the stem 76 of the pilot valve 72 is reciprocated. Therefore, the bore 70 is provided with a terminal annular guide surface 98 which receives therein the sleeve 86. An hermetic seal is established between the external surface of the sleeve 86 and the guide surface 98 by an O-ring l0!) mounted in a suitable annular groove formed within the guide surface. Hence, so long as the shuttle valve 40 remains so disposed that the seat 43 of the seal 42 is in sealing engagement with the face of the shoulder 46, air is exhausted from the chamber 41, to atmosphere, through the fluid discharge unit 83. Therefore, it is to be under-. stood that as the impact head 30 is retracted into the bore 24, entrapped fluid is delivered from the chamber 41 through the ports 84 into the sleeve 86, along the passageway 92, thence through the ports 94 and the bore 96 into the exhaust chamber 64 ultimately to be discharged to atmosphere through the passage 65.

As fluid under pressure is delivered from the chamber 20 to the lower surface 75 of the valve head 74, the impact head 30 continues to be displaced at an accelerating rate until it impactingly engages a laterally extended, annular lip 102 circumscribing the lowermost end surface of the body of the shuttle valve 40. As a practical matter, the lip 102 is formed as an integral portion of the seal 42 which is fitted about the end of the body of the shuttle valve in the manner of a boot.

Due to the impacting of the head 30 against the lip 102, the shuttle valve 40 is displaced from its seated disposition and the seat 43 is lifted from engagement with the shoulder whereupon a pulse of fluid under pressure is released from the chamber 20 as the shuttle valve is drivingly displaced toward the exhaust chamber 64. Since the exhaust chamber 64 is open to atmosphere, through the passage 65, no significant back-pressure is developed within the exhaust chamber as the shuttle valve advances toward the exhaust chamber. Therefore, the shuttle valve 40, as well as the pilot valve 72, is permitted to advance toward the exhaust chamber 64 until the seal 68 is caused to seat against the lip 66 for effecting a sealing of the exhaust chamber 64, HO; 4.

Fluid confined within the chamber 20 is permitted to escape into the bore 24 and pass between the adjacent planar surfaces of the impact head 30 and the lip 102, in order to prevent an establishment of an hermetic seal between the impact head and the shuttle valve 40. The periphery of the planar surface of the head 30 serves as an annular lip 104, FIG. 4, which acts as a pressure face for assisting in precluding establishment of a seal between the head 30 and the shuttle valve 40. In any event, as the seal 68 is seated against the lip 66, the impact head 30 rapidly reverses direction of motion and advances in an impacting stroke toward the opening 26, as best illustrated in FIG. 5.

The pressure of the chamber 20, as the fluid is delivered therefrom to impinge against the impact head 30 within the chamber 41, is directed through the fluid discharge unit 83 to the now sealed exhaust chamber 64. Consequently, the pressure of the fluid confined within the chamber 20 also is delivered to the chamber 64 and is permitted to act downwardly against the transverse surfaces of the valve head 74 for thereby assisting in the accelerating of the impact head 30 as it is displaced in its impacting stroke under the influence of the fluid delivered to impinge directly upon the impact head.

As the pressure of the fluid confined in the exhaust chamber 64 acts against the valve head 74, the pilot valve 72 is advanced downwardly along the bore 70. In order to preclude an entrapment of air beneath the surface 75 of the valve head 74, the sleeve 86 is provided with an elongated relief 106, formedas a flat extended along the sleeves external surface. This relief permits the annular surface 75 of the valve head 74 to communicate with the chamber 41 as the valve head 74 approaches a fully seated disposition at the termination of the impacting stroke for the head 30.

An annular bumper 107, formed as a sleeve of a suitable resilient material, is seated about the sleeve 86 and disposed adjacent to the surface 75 of the valve head 74. The bumper 107 serves to absorb shock as a fixed arresting surface 108, formed as a radially extended, annular stop within the bore of the shuttle valve 40, functions to intercept the pilot valve 72 and arrest its displacement. Consequently, as the impact head 30 is extended,-the surface of the valve head 74 is protected due to the protective effect of the bumper 107 as it engages the surface 108.

OPERATION It is believed that in view of the foregoing description, the operation of the impact tool will be readily understood and it will be briefly reviewed at this point. With the impact tool of the instant invention assembled in a manner hereinbefore described and operatively coupled, at thefitting 22, with a suitable source of pressurized fluid, the seat 43 of the seal 42 is seated in response to the pressure of fluid acting against the face 49 of the shoulder 48 and the tool is caused to assume an impact configuration, as illustrated in FIG. 2.

Operation of the tool is initiated simply by bringing the impact surface 34 of the impact head 30 into operative engagement with a selected working surface, designated 110, in FIG. 3. It is to be understood that the working surface 110 is a surface of any selected body, including a nail head, a surface of a substantially planar sheet, a handheld tool, and the like.

As the impact head 30 engages the surface 110 a retracting stroke for the impact head 30 is initiated as the head is driven through a distance sufficient to cause the valve head 74 of the pilot valve 72 to open the passage 78 between the inlet chamber and the bore 70. As this passage is opened, fluid under pressure is delivered through the passage 78 and thence between the lowermost O-ring 80 and the adjacent surface of the valve head 74, FIG. 3, and permitted to act against the lowermost surface 75 of the valve head 74. As the fluid acts against the surface 75, the impact head 30 disengages the surface 110 and is accelerated as it is advanced in a retracting stroke under the influence of the fluid acting against the head 74 of the pilot valve 72.

As the impact head 30 is caused to complete its retracting stroke, the upper surface of the head 30 is caused to impact against the lip 102 seated about the opposite surface of the shuttle valve 40. The impact force is sufficient for causing the shuttle valve 40 to lift the seat 43 of the seal 42 from engagement with the adjacent surface of the shoulder 46 and seat the seal 68 against the protrusion 66 for sealing the chamber 64. The shuttle valve therefore is lifted against the force of the fluid acting against the face 49 of the shoulder 48. As the seat 43 is lifted, gating of the fluid under pressure is achieved and delivery ofa pulse of fluid from the chamber 20 to the chamber 41 is initiated.

At the instant of impact of the head 30 against the lip 102, the chamber 41 is relatively small, however, fluid is permitted to penetrate between the lips 102 and 104 and impinge against the adjacent surface of the impact head 30 with a force sufficient to displace the head 30 toward its impact disposition and thus effect an elongation of the chamber 41. The hermetic integrity of the chamber 64 is maintained, as the impact head 30 is advanced in an initial portion of an impacting stroke toward the opening 26, due to the force developed within the now expanding chamber 41. This force results from the fact that fluid is delivered to the chamber 41 at a rate greater than that at which it is discharged from the chamber 41 through the ports 84 to the chamber 64. However, the pressure of the fluid within the chamber 64, as it acts against the transverse surface of the valve head 74, assists in accelerating the impact head 30 as the head is displaced toward the opening 26 in its impacting stroke.

As the impact head 30 is advanced toward its impact disposition, the valve head 74 is brought into a sealing relationship with the passage 78, while the lower surstem 76. Hence, the impact head 30 and shuttle valve 40 become an integrated unit with the effect of the pressure of the fluid confined within the chamber 41, as it acts on the shuttle valve 40 being cancelled. Since the pressure of the chamber 64 exceeds that of the bore 24 as it communicates with atmosphere through the opening 26, the head 30 and shuttle valve 40 are advanced as an integrated unit along the bore whereby the shuttle valve 40 is caused to reseat with the seat 43 of the seal 42 sealingly engaging the face of the shoulder 46. As this reseating is achieved a termination of the flow of fluid established from the chamber 20 to the chamber 41 is achieved.

Once the shuttle valve 40 and impact head 30 are advanced, as an integrated unit away from the protrusion 66, the pressure of the fluid confined within the chamber 41 is released, at a controlled rate, through the ports 84 and the exhaust chamber 64, as the exhaust chamber 64 is opened to atmosphere, through the passage 65, due to the displacement of the shuttle valve 40 relative to the protrusions 66. It is important to note that the pressurized fluid is permitted to escape from the chamber 41, through the ports 84 and thence through the passage 65, at predetermined rates, dictated, in part, by the relative sizes of the established passageways, so that the fluid within the chamber 64 remains pressurized so long as the chamber 41 communicates with the chamber 20. Hence, the fluid within the chamber 64 remains under pressure and continuously acts against the uppermost transverse surfaces of the shuttle valve 40 and the valve head 74, so long as the chamber 41 receives fluid from the chamber 20. Consequently, the fluid, as it is passed through the chamber 64, serves to urge the shuttle valve 40 into a seateddisposition wherein the seal 42 sealingly engages the shoulder 46. Once the flow to the chamber 41 in interrupted, the pressure of the fluid within the chamber 64 is reduced to that of atmosphere.

In the event the working surface remains in an operative disposition, at the instant the shuttle valve 40 is reseated, the impact head 30 again is displaced in a retracting direction for again un seating the valve head 74, whereupon the cycle is repeated. However, if the working surface 110 is no longer present for purposes of applying a force against the impact surface 34, no retraction of the impact head 30 is initiated and the tool accordingly assumes an inoperative state.

In view of the foregoing, it should readily be apparent that the present invention provides an improved impact tool particularly adapted for manual operation in achieving a rapid, accurate and efficient impacting operation.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the illustrative details disclosed.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A cyclically operable impact tool for delivering an impacting force output comprising:

A. an hermetically sealed housing;

B. means defining within said housing an hermetically sealed inlet chamber including a pneumatic coupling connecting said chamber with a source of pressurized fluid;

C. means defining within said housing an actuator bore of a tubular configuration disposed adjacent to the inlet chamber;

D. an impact head of a substantially disk-shaped configuration seated for rectilinear reciprocation within said bore adapted to be displaced in a first direction for retracting said head into said bore, and in a second direction for delivering an impacting force output, said impact head being provided with a pressure surface directed into said bore and an oppositely directed impact surface displaceable to an impact disposition as said head is displaced in said second direction; I

E. apneumatically driven shuttle valve supported for axial reciprocation between a first position, wherein said shuttle valve seals said inlet chamber with respect to said bore, and a second position, wherein said shuttle valve permits said inlet chamber to communicate with said bore, whereby fluid under pressure is delivered from said inlet chamber to said bore and into driving engagement with said pressure surface, for thereby displacing said head toward its impact disposition; and

F. a pilot valve coupled with said shuttle valve for initiating displacement of said shuttle valve to its second position in response to a force axially applied to the impact surface of said impact head includ- 1. means defining a concentric bore extended through said shuttle valve in coaxial relation with said impact head,

2. a valve body, including a coaxially related valve head of a substantially cylindrical configuration having a shoulder defining an annular pressure face, and an elongated, coaxially related stem coupled thereto at a root portion circumscribed by said annular pressure face, said body being seated in said concentric bore and adapted to be displaced relative thereto between a valveopening disposition and a valveclosing disposition,

3. rigid connecting means coupling the distal end of said stem to said impact head in coaxial relationship therewith, and

4. means for directing fluid under pressure to impinge on said annular pressure face for driving said valve body in valve-opening displacement for thereby displacing said impact head into im pacting engagement with said shuttle valve, whereby the shuttle valve responsively is driven to its second position.

2. The tool of claim 1 further comprising:

A. an exhaust chamber communicating with said valve head and including therein a fluid discharge port adapted to be opened for venting pressurized fluid as said valve body is driven in valve-opening displacement and sealed for confining pressurized fluid as said shuttle valve is driven to its second position; and

B. means defining a fluid relief path extending from said annular pressure face of said valve head and from said pressure surface of said impact head to said exhaust chamber, whereby a discharge of fluid disposed adjacent to said face and to said pressure surface is accommodated.

3. The tool of claim 2-wherein said means defining said fluid relief path includes:

A. a tubular sleeve concentrically receiving therewithin the stem of said valve body and including radially extended openings disposed adjacent to said pressure surface of said impact head, whereby the internal surface of said sleeve is caused to communicate with said pressure surface;

B. means defining a tubular channel extending from the external surface of said stem, through said valve head, and-terminating at a point adjacent to said exhaust chamber; and C. means defining an elongated relief extended along the external surface of said sleeve, in parallelism with said stem and in continuous communication with said annular pressure face terminating at a point spaced from said radially extended opening such that the elongated relief is caused to communicate with said opening as said impact surface of the impact head is displaced into an impact disposition.

4. The tool of claim 3 wherein'said valve head further includes a transverse pressure face communicating with said exhaust chamber so that as fluid is delivered from said inlet chamber to said bore a passage thereof along a portion of said relief path to said exhaust chamber is accommodated whereby the fluid is permitted to act against said transverse pressure face in cooperation with fluid delivered into driving engagement with the pressure surface of the impact head.

5. The tool of claim 3 wherein said means for directing fluid under, pressure to impinge on said annular pressure faces includes means defining a radial bore extended from said inlet chamber to the concentric bore of said shuttle valve so disposed as to be opened and closed as the valve head reciprocably is displaced.

6. An impact tool comprising:

A. an hermetically sealed housing;

B. means defining within said housing an inlet chamber adapted to communicate with a pressurized source of fluid;

C. means including a tubular surface defining within said housing an elongated bore extending from said inlet chamber and terminating in means defining an output opening manually positionable adjacent to a working surface;

D. means within said bore, disposed between the opening and the inlet-chamber defining a valve seat of an annular configuration coaxially related to said output opening;

E. an axially reciprocable shuttle valve including an elongated body and an annular face circumscribing the external surface thereof adapted to be displaced in a first direction toward said valve seat whereby said annular face is caused to seat on said valve seat for thereby establishing an hermetic seal between said inlet chamber and said output opening, and to be displaced in a second direction, away from the valve seat, for thereby interrupting said hermetic seal;

F. a reciprocably supported impact head seated in said how between said output opening and said shuttle valve and adapted to be reciprocated along an axis extending therebetween;

G. means defining on said impact head an impact delivering surface arranged in a plane parallel to the plane of said opening and adapted to be reciprocably displaced through said opening from a retracted disposition within said bore to an impact ing fluid under pressure to said pressure chamber includes:

ill

disposition externally of said housing, whereby the impact surface is adapted to be extended through the output opening;

H. means defining within said bore an expandible chamber disposed adjacent to said impact head and adapted to communicate with said inlet chamber as the shuttle valve is displaced in said second direction whereby fluid under pressure is delivered from said inlet chamber into an impinging engagement with said impact head; and

. a pilot valve adapted to operatively respond to an engagement of the impact head with a working surface positioned adjacent to said opening, associated with said shuttle valve and adapted to initiate displacement thereof.

7. An impact tool comprising:

A. an elongated housing having a given outside diameter;

B. means concentrically defining within said housing an elongated bore of a diameter slightly less than said given diameter and having a concentric output opening atits terminus and a pressure chamber disposed in a spaced, coaxial relationship with said output opening;

C. a reciprocable impact head seated in said bore adjacent to said opening adapted to be reciprocably displaced between an extended disposition and a retracted disposition relative to the terminus of said bore; and

D. pneumatic means operatively associated with said impact head adapted to impart reciprocation thereto including,

'. an axially reciprocable shuttle valve seated within said bore between said pressure chamber and said impact head adapted to be impactingly engaged by the said impact head and responsively advanced for causing said bore to communicate with said pressure chamber,

ii. connector means coupling said impact head with said shuttle valve,

iii. means for simultaneously delivering fluid under pressure to said bore and to saidpressure chamber, whereby said fluid is caused to act against said impact head and said shuttle valve for driving the impact head and the interconnected shuttle valve toward the output opening of said bore, and

iv. means for arresting displacement of said shuttle valve as it is advanced toward the output end of 50 said bore, whereby displacement of said impact head is arrested through said connector means.

8. The tool of claim 7 wherein said means for deliversource to said pressure chamber through said bore.

9.The tool of claim 8 wherein said impact head defines within said bore a variably dimensioned chamber, said chamber being elongated as fluid under pressure is delivered from said source, and said connector means serves to limit elongation of said variably dimensioned chamber, whereby the connector means and the fluid under pressure within said variably dimensioned chamber serve to integrate the shuttle valve and the impact head into a rigid, integrated structure.

10. The tool of claim9 wherein the diameter of said impact head is substantially as great as that of said bore, whereby said impact head substantially fills said bore as it reciprocably is displaced therealong.

11. An impact tool comprising:

A. a housing including an elongated portion having an outside diameter uniformly decreasing to a given diameter at the terminus thereof;

B. means defining within said portion an elongated bore of a substantially uniform diameter terminating at said terminus;

C. a disk-shaped impact head having a diameter substantially equal to said uniform diameter and supported for rectilinear displacement between an extended position and a retracted position, relative to one end portion of said bore; and

D. bi-stable fluid delivery means disposed within said housing in coaxial alignment with said head for intermittently delivering fluid under pressure to said bore including,

1. an annular valve seat coaxially aligned with said head,

2. a shuttle valve normally seated in engagement with said annular valve seat and supported for axial displacement to a lifted position relative to said seat,

3. means for delivering fluid under pressure to said bore including pilot means connected with said head and responsive to an initial axial displacement of said head in a first direction toward said retracted position for accelerating the head into impacting engagement with said shuttle valve for thereby abruptly lifting said shuttle valve from said annular valve seat, whereby a delivery of fluid under pressure to said bore abruptly in initiated,

4. means including a face of the head responsive to fluid under pressure to said bore for accelerating said head in displacement'in a reverse direction toward said extended position, and

5. means for abruptly interrupting delivery of fluid under pressure to said bore, including impact means connected with said head for impacting against said shuttle valve for driving the shuttle valve into seated engagement with said annular valve seat as the head is accelerated toward said extended position.

12. In an impact tool of a type having a housing including therein means defining an elongated bore, a reciprocable impact head seated in said bore and supported for reciprocation along a rectilinear path extended between a force delivery position near the terminus of said bore and a retracted position coaxially aligned with said terminus, said head being movable in initial displacement from said force delivery position toward said retracted position in response to an ensponsive to impaction with said head for delivering fluid under pressure to said bore, whereby the head is responsively accelerated in displacement in a reverse direction toward said force delivery position; and

C. means for interrupting delivery of fluid to said bore including valve impacting means coaxially aligned with said valve means and supported by said head for striking said valve means as the head is accelerated toward said force delivery position. 

1. A cyclically operable impact tool for delivering an impacting force output comprising: A. an hermetically sealed housing; B. means defining within said housing an hermetically sealed inlet chamber including a pneumatic coupling connecting said chamber with a source of pressurized fluid; C. means defining within said housing an actuator bore of a tubular configuration disposed adjacent to the inlet chamber; D. an impact head of a substantially disk-shaped configuration seated for rectilinear reciprocation within said bore adapted to be displaced in a first direction for retracting said head into said bore, and in a second direction for delivering an impacting force output, said impact head being provided with a pressure surface directed into said bore and an oppositely directed impact surface displaceable to an impact disposition as said head is displaced in said second direction; E. a pneumatically driven shuttle valve supported for axial reciprocation between a first position, wherein said shuttle valve seals said inlet chamber with respect to said bore, and a second position, wherein said shuttle valve permits said inlet chamber to communicate with said bore, whereby fluid under pressure is delivered from said inlet chamber to said bore and into driving engagement with said pressure surface, for thereby displacing said head toward its impact disposition; and F. a pilot valve coupled with said shuttle valve for initiating displacement of said shuttle valve to its second position in response to a force axially applied to the impact surface of said impact head including,
 1. means defining a concentric bore extended through said shuttle valve in coaxial relation with said impact head,
 2. a valve body, including a coaxially related valve head of a substantially cylindrical configuration having a shoulder defining an annular pressure face, and an elongated, coaxially related stem coupled thereto at a root portion circumscribed by said annular pressure face, said body being seated in said concentric bore and adapted to be displaced relative thereto between a valve-opening disposition and a valveclosing disposition,
 3. rigid connecting means coupling the distal end of said stem to said impact head in coaxial relationship therewith, and
 4. means for directing fluid under pressure to impinge on said annular pressure face for driving said valve body in valveopening displacement for thereby displacing said impact head into impacting engagement with said shuttle valve, whereby the shuttle valve responsively is driven to its second position.
 2. a valve body, including a coaxially related valve head of a substantially cylindrical configuration having a shoulder defining an annular pressure face, and an elongated, coaxially related stem coupled thereto at a root portion circumscribed by said annular pressure face, said body being seated in said concentric bore and adapted to be displaced relative thereto between a valve-opening disposition and a valveclosing disposition,
 2. The tool of claim 1 further comprising: A. an exhaust chamber communicating with said valve head and including therein a fluid discharge port adapted to be opened for venting pressurized fluid as said valve body is driven in valve-opening displacement and sealed for confining pressurized fluid as said shuttle valve is driven to its second position; and B. means defining a fluid relief path extending from said annular pressure face of said valve head and from said pressure surface of said impact head to said exhaust chamber, whereby a discharge of fluid disposed adjacent to said face and to said pressure surface is accommodated.
 2. a shuttle valve normally seated in engagement with said annular valve seat and supported for axial displacement to a lifted position relative to said seat,
 3. means for delivering fluid under pressure to said bore including pilot means connected with said head and responsive to an initial axial displacement of said head in a first direction toward said retracted position for accelerating the head into impacting engagement with said shuttle valve for thereby abruptly lifting said shuttle valve from said annular valve seat, whereby a delivery of fluid under pressure to said bore abruptly in initiated,
 3. The tool of claim 2 wherein said means defining said fluid relief path includes: A. a tubular sleeve concentrically receiving therewithin the stem of said valve body and including radially extended openings disposed adjacent to said pressure surface of said impact head, whereby the internal surface of said sleeve is caused to communicate with said pressure surface; B. means defining a tubular channel extending from the external surface of said stem, through said valve head, and terminating at a point adjacent to said exhaust chamber; and C. means defining an elongated relief extended along the external surface of Said sleeve, in parallelism with said stem and in continuous communication with said annular pressure face terminating at a point spaced from said radially extended opening such that the elongated relief is caused to communicate with said opening as said impact surface of the impact head is displaced into an impact disposition.
 3. rigid connecting means coupling the distal end of said stem to said impact head in coaxial relationship therewith, and
 4. means for directing fluid under pressure to impinge on said annular pressure face for driving said valve body in valve-opening displacement for thereby displacing said impact head into impacting engagement with said shuttle valve, whereby the shuttle valve responsively is driven to its second position.
 4. The tool of claim 3 wherein said valve head further includes a transverse pressure face communicating with said exhaust chamber so that as fluid is delivered from said inlet chamber to said bore a passage thereof along a portion of said relief path to said exhaust chamber is accommodated whereby the fluid is permitted to act against said transverse pressure face in cooperation with fluid delivered into driving engagement with the pressure surface of the impact head.
 4. means including a face of the head responsive to fluid under pressure to said bore for accelerating said head in displacement in a reverse direction toward said extended position, and
 5. means for abruptly interrupting delivery of fluid under pressure to said bore, including impact means connected with said head for impacting against said shuttle valve for Driving the shuttle valve into seated engagement with said annular valve seat as the head is accelerated toward said extended position.
 5. The tool of claim 3 wherein said means for directing fluid under pressure to impinge on said annular pressure faces includes means defining a radial bore extended from said inlet chamber to the concentric bore of said shuttle valve so disposed as to be opened and closed as the valve head reciprocably is displaced.
 6. An impact tool comprising: A. an hermetically sealed housing; B. means defining within said housing an inlet chamber adapted to communicate with a pressurized source of fluid; C. means including a tubular surface defining within said housing an elongated bore extending from said inlet chamber and terminating in means defining an output opening manually positionable adjacent to a working surface; D. means within said bore, disposed between the opening and the inlet chamber defining a valve seat of an annular configuration coaxially related to said output opening; E. an axially reciprocable shuttle valve including an elongated body and an annular face circumscribing the external surface thereof adapted to be displaced in a first direction toward said valve seat whereby said annular face is caused to seat on said valve seat for thereby establishing an hermetic seal between said inlet chamber and said output opening, and to be displaced in a second direction, away from the valve seat, for thereby interrupting said hermetic seal; F. a reciprocably supported impact head seated in said bore between said output opening and said shuttle valve and adapted to be reciprocated along an axis extending therebetween; G. means defining on said impact head an impact delivering surface arranged in a plane parallel to the plane of said opening and adapted to be reciprocably displaced through said opening from a retracted disposition within said bore to an impact disposition externally of said housing, whereby the impact surface is adapted to be extended through the output opening; H. means defining within said bore an expandible chamber disposed adjacent to said impact head and adapted to communicate with said inlet chamber as the shuttle valve is displaced in said second direction whereby fluid under pressure is delivered from said inlet chamber into an impinging engagement with said impact head; and I. a pilot valve adapted to operatively respond to an engagement of the impact head with a working surface positioned adjacent to said opening, associated with said shuttle valve and adapted to initiate displacement thereof.
 7. An impact tool comprising: A. an elongated housing having a given outside diameter; B. means concentrically defining within said housing an elongated bore of a diameter slightly less than said given diameter and having a concentric output opening at its terminus and a pressure chamber disposed in a spaced, coaxial relationship with said output opening; C. a reciprocable impact head seated in said bore adjacent to said opening adapted to be reciprocably displaced between an extended disposition and a retracted disposition relative to the terminus of said bore; and D. pneumatic means operatively associated with said impact head adapted to impart reciprocation thereto incLuding, i. an axially reciprocable shuttle valve seated within said bore between said pressure chamber and said impact head adapted to be impactingly engaged by the said impact head and responsively advanced for causing said bore to communicate with said pressure chamber, ii. connector means coupling said impact head with said shuttle valve, iii. means for simultaneously delivering fluid under pressure to said bore and to said pressure chamber, whereby said fluid is caused to act against said impact head and said shuttle valve for driving the impact head and the interconnected shuttle valve toward the output opening of said bore, and iv. means for arresting displacement of said shuttle valve as it is advanced toward the output end of said bore, whereby displacement of said impact head is arrested through said connector means.
 8. The tool of claim 7 wherein said means for delivering fluid under pressure to said pressure chamber includes: A. a source of fluid under pressure; B. means including a valve seat formed on said means for arresting displacement of said shuttle valve adapted to operatively establish and terminate communication between said source of pressurized fluid and said bore as the shuttle valve is displaced in axial reciprocation, whereby fluid under pressure alternately is delivered to said bore; and C. means defining a passageway extending between said bore and said pressure chamber, whereby fluid under pressure operatively is delivered from said source to said pressure chamber through said bore.
 9. The tool of claim 8 wherein said impact head defines within said bore a variably dimensioned chamber, said chamber being elongated as fluid under pressure is delivered from said source, and said connector means serves to limit elongation of said variably dimensioned chamber, whereby the connector means and the fluid under pressure within said variably dimensioned chamber serve to integrate the shuttle valve and the impact head into a rigid, integrated structure.
 10. The tool of claim 9 wherein the diameter of said impact head is substantially as great as that of said bore, whereby said impact head substantially fills said bore as it reciprocably is displaced therealong.
 11. An impact tool comprising: A. a housing including an elongated portion having an outside diameter uniformly decreasing to a given diameter at the terminus thereof; B. means defining within said portion an elongated bore of a substantially uniform diameter terminating at said terminus; C. a disk-shaped impact head having a diameter substantially equal to said uniform diameter and supported for rectilinear displacement between an extended position and a retracted position, relative to one end portion of said bore; and D. bi-stable fluid delivery means disposed within said housing in coaxial alignment with said head for intermittently delivering fluid under pressure to said bore including,
 12. In an impact tool of a type having a housing including therein means defining an elongated bore, a reciprocable impact head seated in said bore and supported for reciprocation along a rectilinear path extended between a force delivery position near the terminus of said bore and a retracted position coaxially aligned with said terminus, said head being movable in initial displacement from said force delivery position toward said retracted position in response to an engagement therewith of a workpiece disposed in juxtaposition with said terminus, the improvement comprising: A. pneumatic means responsive to movement of said head in initial displacement from said force delivery position for pneumatically driving said head in linear displacement in a first direction toward said retracted position; B. axially displaceable valve means positioned within said path and adapted to be impacted by the head as the head is driven in linear displacement toward said retracted position, said valve means being responsive to impaction with said head for delivering fluid under pressure to said bore, whereby the head is responsively accelerated in displacement in a reverse direction toward said force delivery position; and C. means for interrupting delivery of fluid to said bore including valve impacting means coaxially aligned with said valve means and supported by said head for striking said valve means as the head is accelerated toward said force delivery position. 